Cyclic and polyhedral aluminosiloxanes with Al2Si2O4, Al4Si2O6, and Al4Si4O12 frameworks: X-ray crystal structures of [(2,4,6-Me(3)C(6)H(2))N(SiMe(3))Si(OAlBu-i)(OAl(Bu-i)(2))O](2) and [(2,6-Me(2)C(6)H(3))N(SiMe(3))SiO3Al center dot C4H8O2](4)

Reactions of (silylamino)silanetriols RN(SiMe(3))Si(OH)(3) (R = 2,4,6-Me(3)C(6)H(2) (1) and 2,6-Me(2)C(6)H(3) (2)) with i-Bu(2)AlH in 1:1 molar ratio at -78 degrees C afford aluminosiloxanes [RN(SiMe(3))Si(OH)O(OAlBu-i . dioxane)](2) (R = 2,4,6-Me(3)C(6)H(2) (3) and 2,6-Me(2)C(6)H(3) (4)) and [RN(SiMe(3))Si(OAlBu-i)(OAl(Bu-i)(2))O](2) (R = 2,4,6-Me(3)C(6)H(2) (5) and 2,6-Me(2)C(6)H(3) (6)), respectively. While 3 and 4 are eight-membered Al2Si2O4 cyclic compounds, 5 and 6 are drum-shaped aluminosiloxanes with an Al4Si2O6 core. When the same reactions were carried out in 1:2 molar ratio of the reactants at -78 degrees C, only the drum-shaped polyhedral compounds 5 and 6 are isolated. The reactions between the silanetriols and i-Bu(2)AlH in 1:1 molar ratio at 65 degrees C proceed quantitatively to yield the cubic aluminosiloxanes [RN(SiMe(3))SiO3Al . dioxane](4) (R = 2,4,6-Me(3)C(6)H(2) (7) and 2,6-Me(2)C(6)H(3) (8)) with an Al4Si4O12 framework. The X-ray crystal structures of 5 and 8 have been determined.